Fire sprinkler systems are increasingly recognized as necessary safety features in the construction of new buildings and in the upgrading of existing buildings. There is a problem, however, in the installation of fire sprinkler systems.
Many styles of fire sprinkler heads have built-in deflectors that require rotational orientation of the sprinkler head to correctly position the deflector to produce the desired spray pattern when the head operates. All prior art fire sprinkler heads are attached to the piping mains by tapered pipe threads designed to produce a water tight seal using the interference of the tapered threads, plus either or both of a thread tape or thread paste. Thus, it can be appreciated that proper orientation of prior art sprinkler heads can usually only be accomplished by under-tightening the sprinkler heads or over-tightening the sprinkler heads. Overtightening of the tapered pipe threads produces interference between the mating threads, resulting in distortion of the mating parts. Under-tightening over the tapered pipe threads can produce leaks.
U.S. Pat. No. 8,474,472 discloses a pipe fitting useable in the installation of a sprinkler head comprising (a) a body having an open upstream end and an open downstream end, the downstream end having internal threads capable of accepting a threaded male fitting, the body defining an gasket retention area located upstream of the internal threads; and (b) an elongated gasket disposed within the gasket retention area. In the invention, the gasket retention area and the gasket are chosen so that a threaded male fitting threadedly disposed within the downstream end of the body can be rotated within the downstream end of the body 360° while remaining liquid tight for pressures in excess of 300 psig. However, the internal threads of the disclosed pipe fitting are typically made from a thermal plastic, and, so, are vulnerable to assembly stresses and can be damaged on installation of mating part by misaligning threads “cross threading”. Cross threading occurs when two threaded parts are assembled and the threads are not aligned with each other allowing one thread to cut into the other. Cross threaded assemblies are most common when at least one of the mating threads are soft (plastic) and are most common with two tapered threads where initial assembly has substantial thread clearance.
Accordingly, there is a need for a fire sprinkler fitting which avoids the aforementioned in the prior art.